1. Field of the Invention
The present invention relates to a rotation-responsive type one-way clutch which is used in a motor-cycle, a snow mobile or the like, and which exhibits a one-way clutch function when a rotational speed becomes not less than a predetermined speed.
2. Description of the Related Art
In general, a one-way clutch is composed of an outer race and an inner race which are rotated relative to each other, a sprag or a roller for transmitting a torque between the outer race and the inner race, which is adapted to be engaged with a cam surface formed on a raceway surface of the inner race or the outer race so as to transmit a torque in only one direction. Incidentally, this clutch slips in the other direction.
Further, in the above-mentioned embodiments, although it has been explained that the pockets are formed at several circumferential positions, the number of the pockets may be optionally changed, depending upon a required torque capacity. However, it is preferable to provide the pockets at equal circumferential pitches, irrespective of the number thereof. Although it has been explained that the urging spring 5 is fixed to the bent portions 18 of the side plates 10, a cage for holding the urging spring 5 may be provided so as to fix the urging spring 5 to the cage.
For example, Japanese Patent Publication No. S53-8019 discloses such a configuration that a roller is set in a recess formed in an outer race, and when the outer race is rotated clockwise, the roller is locked in the recess under a wedging action, and accordingly the rotation of the outer race is locked, relative to an inner race.
Further, Japanese Patent Laid-Open No. S52-100045 discloses such a configuration that a roller and an auxiliary roller are arranged between an outer race and an input coupling. With this configuration, the auxiliary roller presses the roller under a centrifugal force at a rotational speed not less than a predetermined value by a pressing force by which the roller can be locked under a wedging action with rotation in a predetermined direction. Thus, a one-way clutch function can be exhibited.
The one-way clutch disclosed in the Japanese Patent Publication No. S53-8019 is a typical conventional one using a roller, which is not the one which can be locked in response to a rotational speed.
Further, the Japanese Patent Laid-open No. S52-100045 discloses the one which is locked in response to a rotational speed. However, since an elongated hole which defines an operating range of the auxiliary roller is formed in a component other than the inner race, it is difficult to obtain a desired dimensional accuracy for the one-way clutch, and the necessary number of components becomes larger. Further, there would be such a risk that the auxiliary roller is caught in the elongated hole. Thus, parts such as a plate and an cantilever piece are required while a space for accommodating therein a spring is also required, and accordingly, it is limited to decrease the diameter of the one-way clutch.
In order to solve the above-mentioned problems, as disclosed in Japanese Patent Application No. 2003-101480, there may be provided such a configuration that an urging spring is fitted in a recess in the inner race so as to urge the roller. However, even with this configuration, there would be caused such a risk that the urging spring displaces during operation, diametrically outward, that is, toward the outer race, and then comes off.